Answer to Question #5316 Submitted to "Ask the Experts"

I have a question about eye protection for the occupationally exposed who work in the medical environment. According to the International Commission on Radiological Protection, there is a recommended limit of radiation exposure to the eyes (off memory it's cumulative up to 600 mSv) to reduce the risks of cataract formation. Is there any evidence you can guide me to that shows that wearing lead glasses actually has a benefit in reducing the exposure to one's eyes who works in, say, an angiographical suite or fluoroscopic suite where a number of procedures are peformed daily?

Leaded glasses have been proven to reduce x-ray exposures to the eye for such a long time that it has become dogma. Consequently, if you look for proof in recent scientific literature, you will not find any papers on the subject.

Current commercially available leaded glasses generally are 0.75 mm lead equivalent for the front lens and, if they have optional side shields, the side shields are generally 0.5 mm lead equivalent. Side shields are actually very important for glasses worn by interventional radiologists and cardiologists, due to the fact that most of the scatter and leakage radiation is directed at them from their left side in the usual fluoroscopy lab environment. The side shields intercept this off-axis radiation that is directed towards the lens. For comparison, leaded aprons commonly used for radiation protection in interventional radiology labs are generally 0.5 mm lead equivalent. This reduces the occupational exposures by at least a factor of 90% of the unshielded exposure.

If you wish to obtain scientifically published proof of this fact, you'll have to travel to your nearest radiology library and see if you can locate a copy of these papers:

• Argarwal SK, Friesen EJ, Huddleston AL, Rao RP. The effectiveness of glass lenses in reducing exposure to the eyes. Radiology 129: 810-811; 1978.
   
• Bergstrom K, Jorulf H, Lofroth PO. Eye lens protection for radiological personnel. Radiology 124: 839-840; 1977.
   
• Littleton JT, Durizch ML, Perry N. Radiation protection of the lens for patients and users. Radiology 129: 795-798; 1978.

I did a search of recent literature on this issue and these are the latest papers I could find. Unfortunately, you can get access to only the abstracts online. If you want to read the actual papers, you'll have to do it the old-fashioned way and go to the library.

Mike Bohan, RSO
Yale-New Haven Hospital